Move all code to "gwinc" package

gwinc/__init__.py

gwinc/gwinc.py

gwinc/ifo/Voyager.py

gwinc/ifo/__init__.py

gwinc/ifo/aLIGO.py

gwinc/noise/__init__.py

gwinc/noise/coatingthermal.py

gwinc/noise/newtonian.py

gwinc/noise/quantum.py

gwinc/noise/residualgas.py

gwinc/noise/seismic.py

gwinc/noise/substratethermal.py

gwinc/noise/suspensionthermal.py

gwinc/util.py